载银磷酸锆纱布对烧伤创面常见细菌作用的实验研究

目的 了解载银磷酸锆纱布对烧伤大鼠创面感染常见细菌的抗菌效力。方法制作Wistar大鼠烫伤(以下称烧伤)感染模型，采用试管双倍稀释法测定载银磷酸锆及磺胺嘧啶银的最低抑菌浓度(MIC)及最低杀菌浓度(MBC)。观察大鼠创面用磺胺嘧啶银纱布、普通尢菌纱布、载银磷酸锆纱布(小水洗及水洗20次)后痂下组织的细菌计数和对创面愈合的作用。结果载银磷酸锆对金黄色葡萄球菌、铜绿假单胞菌、大肠竹菌的MIC各为8、8、16mg／L，MBC各为16、8、32mg／L，为磺胺嘧啶银的2～8倍?大鼠创面用未水洗的载银磷酸锆纱布覆盖后，痂下细菌计数比用磺胺嘧啶银纱布低91％，比普通无菌纱布低99％未水洗的载银磷酸锆纱布对创面愈合的作用明显优于其他两种纱布，且其痂下组织细菌计数与水洗20次的效银磷酸锆纱布比较，差异无显著性意义(P＞0．05)。结论载银磷酸锆埘烧伤创面感染常见细菌有较强的抑制和杀灭作用，其敷料可作为治疗措施中新的选择。     

Grain size,crystalline phase and fracture toughness of the monolithic zirconia

PURPOSEThis study evaluated the relationship among translucency, crystalline phase, grain size, and fracture toughness of zirconia.MATERIALS AND METHODSFour commercial zirconia - Prettau^®Anterior^® (PA), Prettau^® (P), InCorisZI (ZI), and InCorisTZI (TZI)- were selected for this study. The bar specimens were prepared to determine fracture toughness by using chevron notched beam method with four-point bending test. The grain size was evaluated by a mean linear intercept method using a scanning electron microscope. X-ray diffraction and Rietveld refinement were performed to evaluate the amount of tetragonal and cubic phases of zirconia. Contrast ratio (CR) was measured to investigate the level of translucency.RESULTSPA had the lowest fracture toughness among other groups (P < .05). In addition, the mean fracture toughness of P was significantly less than that of ZI, but there was no difference compared with TZI. Regarding grain size measurement, PA had the largest average grain size among the groups. P obtained larger grain size than ZI and TZI (P < .05). However, there was no significant difference between ZI and TZI. Moreover, PA had the lowest CR value compared with the other groups (P < .05). This means PA was the most translucent material in this study. Rietveld refinement found that PA presented the greatest percentage of cubic phase, followed by TZI, ZI, and P, respectively.CONCLUSIONThe different approaches are used by manufacturers to fabricate various types of translucent zirconia with different levels of translucency and mechanical properties, which should be concerned for material selection for successful clinical outcome.     

A Double-Blind Randomized Controlled Trial (RCT) of Titanium-13Zirconium versus Titanium Grade IV Small-Diameter Bone Level Implants in Edentulous Mandibles - Results from a 1-Year Observation Period

Background: The use of endosseous dental implants has become common practice for the rehabilitation of edentulous patients, and a two‐implant overdenture has been recommended as the standard of care. The use of small‐diameter implants may extend treatment options and reduce the necessity for bone augmentation. However, the mechanical strength of titanium is limited, so titanium alloys with greater tensile and fatigue strength may be preferable. Purpose: This randomized, controlled, double‐blind, multicenter study investigated in a split‐mouth model whether small‐diameter implants made from Titanium‐13Zirconium alloy (TiZr, Roxolid?) perform at least as well as Titanium Grade IV implants. Methods and Materials: Patients with an edentulous mandible received one TiZr and one Ti Grade IV small‐diameter bone level implant (3.3 mm, SLActive®) in the interforaminal region. The site distribution was randomized and double‐blinded. Outcome measures included change in radiological peri‐implant bone level from surgery to 12 months post‐insertion (primary), implant survival, success, soft tissue conditions, and safety (secondary). Results: Of 91 treated patients, 87 were available for the 12‐month follow‐up. Peri‐implant bone level change (?0.3 ± 0.5 mm vs ?0.3 ± 0.6 mm), plaque, and sulcus bleeding indices were not significantly different between TiZr and Ti Grade IV implants. Implant survival rates were 98.9 percent and 97.8 percent, success rates were 96.6 percent and 94.4 percent, respectively. Nineteen minor and no serious adverse events were related to the study devices. Conclusion: This study confirms that TiZr small‐diameter bone level implants provide at least the same outcomes after 12 months as Ti Grade IV bone level implants. The improved mechanical properties of TiZr implants may extend implant therapy to more challenging clinical situations.     

Mechanical testing of thin-walled zirconia abutments

Although the use of zirconia abutments for implant-supported restorations has gained momentum with the increasing demand for esthetics, little informed design rationale has been developed to characterize their fatigue behavior under different clinical scenarios. However, to prevent the zirconia from fracturing, the use of a titanium connection in bicomponent aesthetic abutments has been suggested.

Objective:

Mechanical testing of customized thin-walled titanium-zirconia abutments at the connection with the implant was performed in order to characterize the fatigue behavior and the failure modes for straight and angled abutments.

Material and Methods:

Twenty custom-made bi-component abutments were tested according to ISO 14801:2007 either at a straight or a 25º angle inclination (n=10 each group). Fatigue was conducted at 15 Hz for 5 million cycles in dry conditions at 20ºC±5ºC. Mean values and standard deviations were calculated for each group. All comparisons were performed by t-tests assuming unequal variances. The level of statistical significance was set at p≤0.05. Failed samples were inspected in a polarized-light and then in a scanning electron microscope.

Results:

Straight and angled abutments mean maximum load was 296.7 N and 1,145 N, the dynamic loading mean F^max was 237.4 N and 240.7 N, respectively. No significant differences resulted between the straight and angled bi-component abutments in both static (p=0.253) and dynamic testing (p=0.135). A significant difference in the bending moment required for fracture was detected between the groups (p=0.01). Fractures in the angled group occurred mainly at the point of load application, whereas in the straight abutments, fractures were located coronally and close to the thinly designed areas at the cervical region.

Conclusion:

Angled or straight thin-walled zirconia abutments presented similar F^max under fatigue testing despite the different bending moments required for fracture. The main implication is that although zirconia angled or straight abutments presented similar mechanical behavior, the failure mode tended to be more catastrophic in straight (fracture at the cervical region) compared to angled abutments.     

锆离子对牙髓干细胞增殖及成骨分化的影响

目的研究Zr4＋对大鼠牙髓干细胞增殖及矿化功能的影响。方法四甲基偶氮噻唑盐（MTT）检测Zr4＋对牙髓干细胞增殖的影响,碱性磷酸酶活性测定法检测其对牙髓干细胞成骨分化的影响。结果Zr4＋在1×10-9-1×10-5m01／L的浓度范围内均能够促进牙髓干细胞的增殖及分化。结论锆离子对牙髓干细胞的增殖和分化具有促进作用,含锆物质适于应用于口腔护理。     

Comparison of oral micro-adhesion on polyetheretherketone,zirconium dioxide,and pure titanium abutment北大核心

BACKGROUND: There are some aesthetic and biomechanical problems in the application of zirconium dioxide and pure titanium abutment in the anterior teeth area. A kind of aesthetic abutment material conforming to biomechanics needs to be studied urgently. OBJECTIVE: To compare the adhesion of Porphyromonas gingivalis and whole saliva on the surface of polyetheretherketone (PEEK), zirconium dioxide (ZrO2), and pure titanium (Ti). METHODS: Specimens with the shape of a disk were prepared from PEEK, ZrO2, and Ti. The surface morphology feature was observed by scanning electron microscope. Surface roughness was determined by atomic force microscope. Contact angle was measured using contact angle measuring instrument. The adhesion force of Porphyromonas gingivalis on the surface of materials was measured using an atomic force microscope probe. The initial bacterial adhesion on materials in the suspension of Porphyromonas gingivalis and whole saliva was evaluated by scanning electron microscope and Cell Counting Kit-8 assay. RESULTS AND CONCLUSION: (1) Scanning electron microscope showed that the surface of the PEEK and Ti specimen was grooved, and the groove of PEEK was more than that of Ti, and there were a few microholes on the surface of ZrO2. Atomic force microscopy showed that parallel groove undulations were observed on the surfaces of the three specimens. The groove peak and valley structure of PEEK and ZrO2 was more prominent than that of Ti, and the porous concave and convex structure of the ZrO2 surface was more than that of PEEK. (2) The surface roughness of ZrO2 was greater than that of Ti (P < 0.05). The pairwise comparison between other groups showed no significant difference (P > 0.05). There was no significant difference between the contact angles of the three groups (P > 0.05). (3) A significantly lower adhesion force was identified for PEEK than for ZrO2 and Ti (P < 0.05). (4) The results of scanning electron microscope observation showed that the bacterial adhesion on the PEEK surface was the least, while that on the Ti surface was the most. The Cell Counting Kit-8 assay result showed that the initial bacterial adhesion on the surface of PEEK was significantly lower than that on the surface of ZrO2 and Ti (P < 0.05). (5) The results suggest that PEEK has more advantages to inhibit initial bacterial adhesion than conventional abutment materials such as ZrO2 and Ti. © 2022, Publishing House of Chinese Journal of Tissue Engineering Research. All rights reserved.     

个性化全瓷基台在前牙种植修复中的应用

目的探讨个性化全瓷基台在前牙区种植修复的美学效果。 方法临床上收集51例前牙缺失患者（共植入60枚种植体）作为研究对象,根据患者意愿,26例选择个性化金属纯钛基台纳入对照组即：个性化钛基台+全瓷冠修复（30枚）;25例患者选择个性化全瓷基台纳入实验组即：个性化全瓷基台+全瓷冠修复（30枚）。通过两组对照研究,术后1、6、12个月复诊,分别记录红白复合美学指数、牙龈指数及菌斑指数,将数据进行统计学分析。 结果术后1、6个月红白美学指数差异无统计学意义;术后12个月比较：（1）红色美学指数：实验组（30例）高于对照组（28例）,差异有统计学意义（χ²= 6.696,P= 0.020）;（2）白色美学指数：实验组（30例）高于于对照组（29例）,差异有统计学意义（χ²=6.634,P= 0.021）。术后1个月菌斑指数和牙龈指数差异无统计学意义;术后6个月两组比较菌斑指数（t= 3.128,P= 0.003）和牙龈指数（Z=-3.537,P= 0.000）差异均有统计学意义;术后12个月两组比较菌斑指数（t= 3.027,P= 0.004）和牙龈指数（Z=-6.785,P= 0.000）差异均有统计学意义。 结论在前牙种植美容修复中,个性化全瓷基台较钛基台优势明显,值得临床推广。     

两种粘接剂对氧化锆全瓷冠粘接效果的比较

目的 比较树脂加强型玻璃离子和自粘接树脂型水门汀粘接剂对氧化锆全瓷冠的临床粘接效果.方法 选取66例患者100颗需要进行氧化锆全瓷冠修复的患牙,随机分为两组(n=50),分别采用3M RelyXTMLuting树脂加强型玻璃离子粘固剂(RelyX L组)和3M RelyXTM U200通用自粘接树脂水门汀(RelyX U组)粘接.两年后复查,检查修复体的固位情况及边缘密合性,比较两组修复的成功率.结果 RelyX L组修复成功率98.0％;RelyX U组修复成功率100.0％,两组间差异无统计学意义.结论 在进行氧化锆全瓷冠修复时,采用树脂加强型玻璃离子和自粘接树脂型水门汀粘接剂均能取得良好的临床粘接效果.